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Send away! I created a username/password for Earl, and sent it his way. Same thing with a lot of folks that have used Perry's Cantina in the past.
I don't think the format change scared people away, because posting in the other Cyburbia forums has increased quite a bit since vBulletin replaced Discus. The forums aren't as busy as I'd like to see them, though, but things are definitely more active.